Analytical and experimental heat transfer techniques are applied to a number of research and clinical situations in order to further the understanding of modeling of heat transfer processes in biological systems. Contributions of metabolic heat generation and blood flow in the overall energy balance on tissue are considered. Bio-heat transfer models have been developed and successfully applied to the determination of regional blood flow rates. The effect of various anesthetics on the behavior of blood flow and metabolic heat generation are being considered. Bio-heat transfer aspects of central and peripheral rewarming patterns in postoperative cardiac patients has been studied. Modeling of heat and mass transfer in pulmonary system is under way.